Predictive, preventive and personalized medicine is the common goal of patients and health-care providers. The completion of the human genome project and genetic screenings of several hundreds of human cancers over the last years, have led to the identification of hundreds of "driver" kinase mutations in different types of cancers. To take advantage of the information emerging from these studies, our long-term efforts are directed towards applying advanced systems biology methodologies to better define the consequences of combined mutations in head and neck squamous cell carcinomas (HNSCC). Such an approach will allow patient tailored therapies to be prescribed in the future, resulting in higher cure rates and lower toxicity. In addition to oncogenic mutations, another important regulatory component of cell signaling is represented by the generation of reactive oxygen species (ROS) in response to growth factors initiated signaling, radiation therapy, drugs/xenobiotics metabolism and other factors. The combined contribution of oncogenic mutations and oxidation of signaling proteins in HNSCC or other cancers has received little attention. The redox regulation of signaling networks is particularly important in the context of radiation therapies as little is known about the interaction of radiation induced ROS and signaling pathways that promote cell death or cell proliferation. To investigate the redox regulation of signaling networks that control tumor growth and the response to radiation and drug therapies, we describe here a cross-disciplinary, translational approach based on i] proteomics methodologies, ii] specific instrumentation for cellular stimulation with growth factors with millisecond time resolution, iii] first time use of highly specific molecular probes for the detection of sulfenic acid containing proteins as key intermediates in redox signaling, and iv] computational methods to integrate and evaluate the massive amount of data generated by the proteomics approach. We propose to define targets of protein oxidation and protein phosphorylation under normal (EGF stimulation) and therapeutic conditions (radiation plus or minus Erlotinib) using an isogenic radiation-resistant model of HNSCC. Also, we describe a series of follow-up studies to assess the consequences of oxidative modification on protein function and radiation resistance phenotype for a selected number of signaling proteins identified as oxidized by the proteomics studies. The outcome of this project will yield a systems-level understanding of phospho- and oxidative signaling following radiation, both in sensitive and resistant cell lines. This proposal combines multiple sets of experimental data, modeling, and theory for developing a systems-level understanding of properties and biological consequences of these perturbations.